Ballistic disc

ABSTRACT

Spherically curved ballistic discs of substantially circular periphery, which are of greater thickness at the central portion than at the peripheral portion are positioned in an apertured casing with the concave sides of the discs facing outwardly. An explosive train in the casing serves to propel the disc toward the target at very high velocities and, during initial flight, the concave disc configuration inverts to a convex streamlined shape. The disc does not disintegrate prior to impact, and retains more than 95 percent of its original mass.

United States Patent Dunetz et a1. 1 1 Oct. 21, 1975 15 BALLISTIC DISC 2,379,257 6/1945 Scott 102/5 3,386,380 6/1968 Francis 102/23 [75] Inventors: Bryant Dune", Churchvlne; 3,489,088 1/1970 Ballmoos et a1. 102/61 Seymour Km'lman, Aberdeen, both 3,517,615 6/1970 Jacobs 102/22 of 3,683,809 8/1972 Burkle 102/24 R Assigneez The United States of America as 3,695,141 10/1972 Kronman et a1. 102/92.l

represented by the Secretary of the Army, Washi DC Primary ExaminerRobert F, Stahl I Attorney, Agent, or FirmNathan Edelberg; Robert P. [22] Ffled' Sept 1973 Gibson; Vincent W. Cleary [21] Appl. No.: 397,527

[44] Published under the Trial Voluntary Protest [57] ABSTRACT g ggg ggg January 1975 as document Spherically curved ballistic discs of substantially circular periphery, which are of greater thickness at the [52] U S Cl l02/92 lO2/8 10268, central portion than at the peripheral portion are posi- 102/69 tioned in an apertured casing with the concave sides [51] Int Cl 2 F42B 23/06 of the discs facing outwardly. An explosive train in the [58] Fie'ld 24 38 61 casing serves to propel the disc toward the target at 102mg 1 very high velocities and, during initial flight, the concave disc configuration inverts to a convex stream- [56] References Cited lined shape. The disc does not disintegrate prior to im- UNITED STATES PATENTS pact, and retains more than 95 percent of its original mass. 1,244,298 l0/l917 Cutting 102/61 1,301,098 4/1919 Bull 1. 102/5 12 Claims, 4 DrawingFigures- 36 Z 4 6 l l0 US. Patent Oct. 21, 1975 BALLISTIC DISC STATEMENT OF GOVERNMENT INTEREST The invention described herein may be manufactured, used and licensed by or for the Government for governmental purposes without the payment to us of any royalty thereon.

CROSS-REFERENCE TO RELATED PATENT US. Pat. No. 3,695,141, Explosive Ordnance Demolition Weapon, issued Oct. 3, 1972 to the United States of America as represented by the Secretary of the Navy, on an application filed Nov. 6, 1970, by Seymour Kronman (joint inventor of the present application), Dana E. Spencer and Larry D. Henderson.

BACKGROUND OF THE INVENTION This invention relates generally to a spherically curved metallic ballistic disc capable of being fired at high velocities and altering its shape, upon being fired, to a convex configuration capable of inflicting great anti-personnel and anti-materiel damage and of piercing armor plate of substantial thickness. The disc does not disintegrate prior to impact.

This invention also relates to apertured casings for simultaneously launching a plurality of such ballistic discs. A launcher for a single ballistic disc in accordance with the present invention is described in the above-referenced Kronman et al. US. Pat. No. 3,695,141. An ordnance device for simultaneously launching a multiplicity of our ballistic discs will be described hereafter.

We are aware of US. Pat. No. 3,386,380, G. F. Francis, dated June 4, 1968, wherein the propulsion of flat circular metallic discs by an explosive is disclosed, e.g., for use against enemy satellites and missiles, or as a self-destruct device for disabled friendly satellites and missiles. We are also aware that flat circular deformable discs of uniform thickness, sandwiched between two layers of explosives have been disclosed as explosive wave shapers in U.S. Pat. No. 3,517,615, S. J. Jacobs, assignor to the United States of America as represented by the Secretary of the Navy, dated June 30, 1970. However, the discs of these patents lack the concave-convex configuration of our ballistic discs and are neither intended for or capable of assuming the shape of streamlined projectiles for high-velocity flight upon being launched by an explosive propellant.

SUMMARY OF THE INVENTION The ballistic disc of our invention is made of metallic material, preferably steel, e.g., mild steel, such as SAE 1020. It is spherically curved and is thicker at its central portion than at its peripheral portion, is mounted with its concave side facing the target and, upon firing, inverts to a streamlined elliptical ogive configuration during flight toward the target. The casing, which may be of frustoconial, cylindrical or other suitable shape, may be of plastic (e.g., polymethylmethacrylate) or other suitable material. The curved side of the casing has a plurality of round apertures, preferably arranged in a circle or in several parallel circles. Each aperture has yieldingly mounted therein a ballistic disc along its thin periphery, either snapped in or adhesively connected.

The ballistic discs are launched by a suitable high explosive propellant disposed inside the casing, e.g., percent HMX (cyclotetramethylene tetranitramine) and 30 percent TNT, with or without a booster such as tetryl (tetranitromethyl aniline). Disc velocities of 7,00010,000 feet per second were attained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an enlarged (not to scale) cross-sectional view of the ballistic disc portion of the present invention;

FIG. 2 is a schematic side elevation (not to scale) of the projectile (deformed ballistic disc) after firing;

FIG. 3 is a side elevation of a weapon or ordnance device including a number of ballistic discs; and

FIG. 4 is a schematic vertical section through the embodiment of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings wherein like reference characters designate identical or corresponding parts throughout the several views, and more particularly to FIG. 1, there is shown our ballistic disc 10 made of metal, preferably a hard metal such as steel (e.g., mild steel SAE 1020), wherein the central portion is of greater thickness than the thickness around the disc periphery. As shown in FIG. 1, in which the shape of the disc is enlarged and exaggerated for purposes of clarity, disc 10 has an outer spherical face 12, an inner spherically curved central portion 14 of constant thickness extending approximately one-half of the total disc diameter, between points 16 and 18, and a peripheral portion 20 extending radially outwardly from the central portion and being of lesser thickness than the cen tral portion. The discs peripheral portion 20 has an inner surface which conforms to a frusto-conical configuration so that the thickness of the peripheral portion 20 diminishes at a constant rate from the thickness of the central portion toward a predetermined lesser thickness at the peripheral edge 22 of the disc. An angle 0 is formed at the peripheral edge 22 between the inner boundary line 24 of the peripheral portion 20 and the chord 26 which connects two diametrically opposite points located on edge 22.

The following table indicates manufacturing details of representative ballistic discs, in accordance with our invention, without, however, limiting the scope of our invention thereto.

TABLE I Radius of sphere corresponding Disc Weight Thickness Thickness Angle 0 to curvature Example Diameter (grains) at Center at Edge at Edge of outer face I 1.5" .056" .022" 1439 1.687" II 1.0" 53 .037" .014" 1145 1.125" 111 .75" 23 .028" .011 1355 .875" IV .50" 5.5 .018" .008" 1445 .564"

TABLE I-continued Radius of sphere corresponding Disc Weight Thickness Thickness Angle 6 to curvature Example Diameter (grains) at Center at Edge at Edge of outer face Preferred material: mild steel, SAE 1020 As disclosed in the above-referenced Kronman et al. U.S. Pat. No. 3,695,141, a 1%. inch diameter ballistic disc in accordance with the present invention is capable of total penetration through 0.75 inch of mild steel plate while a 2 7/8 inch diameter ballistic disc is capable of total penetration through 1.75 inches of mild steel plate, When the weapon is fired, the concave disc configuration converts to a convex streamlined elliptical-ogival configuration shown in FIG. 2, at about a distance of one disc diameter from the point at which it was fired, thus further contributing to the attainment of the extremely high disc velocities and great penetrating power of the weapon. The device may be effectively fired at close range or long range. The disc does not disintegrate prior to impact, and retains more than 95 percent of its original mass.

An ordnance device capable of simultaneously launching a multiplicity of our ballistic discs for 360 area coverage as shown in FIGS. 3 and 4. It can be used as the warhead of a missile, a submissile, a bomblet, artillery shell, or infantry grenade, or can be used as a stationary weapon in the nature of a land mine. In the presently preferred frusto-conical configuration (which may be replaced by other suitable shapes, such as cylindrical (not shown) of casing 30, its curved side wall 32 has a plurality of circular apertures 34, arranged in a circle 36 or, preferably, in several parallel circles, 36, 38, 40. As shown, there are 24 such apertures, arranged in three circles, but it will be understood that this number is merely exemplary. The outer dimensions of the frustocone, as illustrated, are 3 9/16 inches (approximately 90mm.) diameter at bottom, 2.29 inches diameter at top, slant height of curved surface of revolution 4 1/16 inches; thickness of side wall 32 is 3/16 inch and of top wall 42 is inch; diameter of each aperture is approximately 1 inch.

There is seated in each aperture a ballistic disc 10, as shown perspectively in FIG. 3, and diagrammatically in dashed lines in FIG. 4, with its concave face facing outwardly. For ease of illustration, FIG. 4 does not reflect the staggered arrangement of apertures 34 as shown in FIG. 3; either arrangement may obviously be used.

A suitable adhesive, such as Eastman 910, a thickened and plasticized cyanoacrylate, may be used to adhere disc 10 to the periphery of aperture 34; however, the adhesive can be dispensed with if disc and aperture are machined with sufficient precision to snap the one into the other.

For ease of manufacturing, a plastic material, such as polymethyl methacrylate (Plexiglass; Lucite") may be used for the casing 30, but other suitable plastics or nonplastics materials may obviously be substituted.

In the device, as illustrated, there is provided an explosive train 44, comprising three cylindrical tetryl pellets 46, 48, 50 (being, respectively, inch, 1 inch, and #2 inch height and diameter) at the respective height levels of aperture circles 36, 38, 40; the pellets are connected to each other by a Primacord 52; the explosive train is spaced from the top plate 42 by suitable spacer means 54 (shown in dashed lines). A suitable detonator (not shown) is provided ator near the open base of casing 30. Additional explosive propellant (not shown), such as a mixture (e.g., 50:50) of RDX (cyclotrimethylene trinitramine) and pentolite [which in turn is a mixture of 50-90 percent TNT and 10-50 percent PETN (pentaerythritol trinitrate)}, or a mixture of I-IMX and RDX, e.g., :30, may be packed inside casing 30.

For a single shot device, the casing and propellant system of above-referenced Kronman et al. U.S. Pat. No. 3,695,141, may be used for launching our ballistic disc 10, with or without a supporting platform.

The following table illustrated the effectiveness of our ballistic disc against armor plate, 1% inch ballistic discs (weight 170 grains each), produced in accordance with Example 1, above, were fired against ,41 inch steel plate at various distances, and the effectiveness was measured in terms of the sizes of the holes produced in the armor plate.

TABLE II Distance in Feet Hole Size (in Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described herein.

We claim:

1. A substantially spherically curved metallic highvelocity ballistic disc of substantially circular periphery, said disc being non-disintegrating prior to impact and having a concave and a convex side, the curved central portion of said disc being of greater thickness than the peripheral portion of said disc, said disc prior to firing being yieldingly retainable about its periphery within a circular aperture of a casing with the concave side of said disc facing outwardly, and said disc upon the diameter of said disc.

5. A ballistic disc according to claim 1, said disc being of steel.

6. A ballistic disc according to claim 5, wherein said steel is mild steel.

apertures are arranged in at least one circle in the side of said frustocone.

10. A munition according to claim 9 wherein said apertures are arranged in a plurality of parallel circles.

11. A munition according to claim 7 wherein said ballistic discs are adhesively connected to said casing.

12. A munition according to claim 7, and including an explosive propellant within said casing. 

1. A substantially spherically curved metallic high-velocity ballistic disc of substantially circular periphery, said disc being non-disintegrating prior to impact and having a concave and a convex side, the curved central portion of said disc being of greater thickness than the peripheral portion of said disc, said disc prior to firing being yieldingly retainable about its periphery within a circular aperture of a casing with the concave side of said disc facing outwardly, and said disc upon being fired assuming a convex streamlined shape.
 2. A ballistic disc according to claim 1, wherein said curved central portion is of substantially uniform thickness.
 3. A ballistic disc according to claim 1, wherein the diameter of said curved central portion is about 1/2 of the diameter of said disc.
 4. A ballistic disc according to claim 2, wherein the diameter of said curved central portion is about 1/2 of the diameter of said disc.
 5. A ballistic disc according to claim 1, said disc being of steel.
 6. A ballistic disc according to claim 5, wherein said steel is mild steel.
 7. A munition comprising a casing having a curved side, a plurality of round apertures in said side, and ballistic discs according to claim 1 seated in said apertures.
 8. A munition according to claim 7 wherein said casing is of plastics material.
 9. A munition according to claim 7 wherein said casing is of frustoconical configuration and wherein said apertures are arranged in at least one circle in the side of said frustocone.
 10. A munition according to claim 9 wherein said apertures are arranged in a plurality of parallel circles.
 11. A munition according to claim 7 wherein said ballistic discs are adhesively connected to said casing.
 12. A munition according to claim 7, and including an explosive propellant within said casing. 